The present application relates to a displays device and display method, and particularly, relates to a display device and display method suitable to be employed in the case of displaying an image using matrix driving.
A simple matrix (passive matrix) method is employed for driving emission elements such as LEDs (Light Emitting Diodes), liquid crystal elements, or the like which are provided on intersecting points by disposing X electrodes and Y electrodes in a grid pattern, and turning on/off these electrodes in accordance with a certain timing. With liquid crystal devices employing the simple matrix method, few electrodes are employed, manufacturing is facilitated, and accordingly, price is less inexpensive as compared to products employing the active matrix method. With a display panel employing the simple matrix method, the emission duration of one pixel at one frame of an image can be expressed asdisplays duration of one frame/number of scan lines.
Description will be made regarding a display device 1 employing an existing simple matrix method with reference to FIG. 1. The display device 1 is configured of a controller 11, display portion 12, data driver 13, and scan driver 14. In response to input of the image data corresponding to an image to be displayed on the display portion 12, the controller 11 controls the data driver 13 and scan driver 14.
With the display portion 12, wiring lines for connecting the outputs from the data driver 13 and scan driver 14 to electrodes included in an emission element 21 are wired around in a vertical and horizontal grid pattern. Image signal wiring lines connected to the output from the data driver 13 will be referred to as data wiring lines, and scan signal wiring lines connected to the output from the scan driver 14 will be referred to as scan wiring lines. Multiple emission elements 21 are provided on an intersection portion between a data wiring line and scan wiring line. The display portion 12 displays an image using emission of the emission element 21 driven bid the data driver 13 and scan driver 14.
That is to say, in a case wherein the display portion 12 is monochrome display, data wiring lines equivalent to the number of pixels arrayed in the horizontal direction at one frame are provided in a column manner (vertical direction in FIG. 1), and are connected to the output of the data driver 13. On the other hand, in a case wherein the display portion 12 is full-color display, there is a need to supply signals equivalent to three colors worth of R (Red), G (Green), and B (Blue) to each pixel, and accordingly, data wiring lines which are triple the number of pixels arrayed in the horizontal direction at one frame are provided in a column manner, and are connected to the output of the data driver 13. Also, even in a case wherein the display portion 12 is monochrome display or full-color displays, scan wiring lines equivalent to the number of horizontal lines of one frame are provided in a line manner (horizontal direction in FIG. 1), and are connected to the output of the scan driver 14.
With the display portion 12, the emission elements 21 equivalent to the number of pixels are provided in the case of monochrome display, and the emission elements 21 which are triple the number of pixels are provided in the case of full-color display, and each of the emission elements 21 includes a data electrode connected to the output of the data driver 13, and a scan electrode connected to the output of the scan driver 14.
With the display device 1 employing the simple matrix method, LEDs (Light Emitting Diodes) can be employed as the emission elements 21. Also, an arrangement may be made wherein with the display device 1, liquid crystal is employed as the emission elements 21, and a display method such as the STN (Super Twisted Nematic) method, DSTN (Dual-scan Super Twisted Nematic) method, or the like, which are the simple matrix methods, is employed.
In a case wherein each of the emission elements 21 of the display portion 12 is distinguished, each will be referred to as “emission element 21-n-m”, wherein its line is n, and its column is m. Specifically, in FIG. 1, the emission elements 21 provided on the top line of the display portion 122 are referred to as an emission element 21-1-1, emission element 21-1-2, and soon. Similarly, the emission elements 21 provided on the next line are referred to as an emission element 21-2-1, emission element 21-2-2, and so on, and the emission elements 21 further provided on the next line are referred to as an emission element 21-3-1, emission element 21-3-2, and so on. In a case wherein each of the emission elements 21 of the display portion 12 is not distinguished, each will be referred to simply as “emission element 21”.
The data driver 13 obtains one line worth of data signals indicating information to be displayed on the display portion 12 at a time, latches (holds) one line worth of the data signals corresponding to the respective pixels internally, performs PWM (Pulse Width Modulation) control based on the latched data signals, converts the data signals into the corresponding current values, and applies electric charge to the data electrode of the emission elements 21 at predetermined timing. Description will be made later regarding the detailed configuration of the data driver 13 with reference to FIG. 2.
The scan driver 14 is configured of shift registers equivalent to the number of horizontal lines, and receives supply of a scan start pulse having the same pulse width as the scan clock at the top of each frame from the controller 11. The pulse Width (one cycle of ON/OFF) of the scan clock is equal todisplay duration of one frame/number of scan lines.
With the respective shift registers of the scan driver 14, the supplied scan start pulse is shifted from the shift register corresponding to the first line to the shift register corresponding to the lower line thereof in order based on the scan clock. Thus, a switching element (e.g., switching transistor) connected to the shift register which receives the ON signal of the scan start pulse is turned to ON, the corresponding line is scanned, and the pixels of the relevant line are lit corresponding to the data signal.
The scan electrodes of the emission elements 21 disposed in a matrix manner at the display portion 12 are common for each line, and while the switching element connected to the scan wiring is ON, the emission elements 21 of the line thereof are lit based on the current value supplied from the data driver 13. ON/OFF action of the scan driver 14 and emission timing for each line will be described later with reference to FIGS. 3 and 4.
FIG. 2 illustrates the further detailed configuration of the data driver 13. There are provided shift registers 41-1 through 41-a, latches 42-1 through 42-a, comparators 43-1 through 43-a, and drivers 44-1 through 44-a, which are equivalent to the number of data wiring lines (the number of data wiring lines wired from the data driver 13 is taken as a, here), which are equivalent to the number of pixels arrayed in the horizontal direction at one frame, or triple the number of pixels, and a counter 45 for counting the number of clocks employed for PWM control by the comparators 43-1 through 43-a. 
Hereafter, in a case wherein the shift registers 41-1 through 41-a are not individually distinguished, each will be referred to simply as “shift register 41”, and in a case wherein the latches 42-1 through 42-a are not individually distinguished, each will be referred to simply as “latch 42”. Similarly, in a case wherein the comparators 43-1 through 43-a are not individually distinguished, each will be referred to simply as “comparator 43”, and in a case wherein the drivers 44-1 through 44-a are not individually distinguished, each will be referred to simply as “driver 44”.
The shift register 41-1 shifts the image data signal supplied from the controller 11 to the shift register 41-2. The subsequent shift registers of the shift register 41-2 and thereafter similarly supply the image data signal to the next shift register. When image data signals on a certain line, i.e., the signals corresponding to emission intensity of the frame including a pixels of one line, or a sub pixels corresponding to each of RGB making up a pixel, are all transmitted to the shift registers 41-1 through 41-a, the shift registers 41-1 through 41-a supply the signals thereof to the latches 42-1 through 42-a to store (latch) these. Now, sub pixels indicate elements making up a pixel, and at the time of monochrome display, the number of sub pixels is equal to the number of pixels, and at the time of color display, the number of sub pixels is triple the number of pixels.
In response to supply of a data latch clock, the latches 42-1 through 42-a supply the stored data signal to the comparators 43-1 through 43-a at predetermined timing simultaneously.
The comparator 43 controls the driver 44 which drives the emission elements 21 using PWM (Pulse Width Modulation) control. That is to say, the comparator 43 controls the emission period of the emission elements 21 by controlling duration wherein the driver 44 is ON within a predetermined period (PWM cycle) based on the data signal supplied from the latch 42. The driver 44 drives the emission elements 21 based on the control of the comparator 43. Also, while the emission elements 21 are driven by the comparator 43 and driver 44, the shift register 41 and latch 42 perform transmission and latching of the data of the next line.
Next, description will be made regarding emission timing control of the emission elements 21 and transmission of data with reference to FIGS. 3 through 5.
FIG. 3 illustrates the scan start pulse, scan clock, and the emission timing of each line. The scan clock is a clock for controlling the emission start timing of each line, and in a case wherein the emission duration of each line is T, i.e., in the case ofT=display duration of one frame/number of scan lines, the emission start timing of each line is also shifted by T. 
When receiving supply of the scan start pulse at the top of each frame from the controller 11, the scan driver 14 counts the scan clock, light-emits the first line by the duration T from point-in-time t1 to point-in-time t2, following which light-emits the second line by the duration T from point-in-time t2 to point-in-time t3, and hereafter, similarly, light-emits the b'th line (b is a positive integer which is equal to or greater than 3 and equal to or less than the number of lines of one frame) by the duration T from point-in-time tb to point-in-time t(b+1). 
Description will be made with reference to FIG. 4 regarding the operation of the scan driver 14 for light-emitting each line the timing described with reference to FIG. 3.
The scan driver 14 is configured of shift registers 61-1 through 61-c (c is the number of horizontal lines making up one frame), and switching transistors 62-1 through 62-c corresponding to the respective shift registers thereof. When the scan start pulse is supplied to the shift transistor 61-1, the scan start pulse is supplied to the shift register 61-1, the corresponding switching transistor 62-1 is turned ON, and voltage is applied to the respective scan electrodes of the emission elements 21 on the first line. Subsequently, based on the output from the data driver 13 at that time, each of the emission elements 21 on the first line is lit for predetermined duration.
That is to say, as described with reference to FIG. 2, in a case wherein image data signals corresponding to one line are sequentially supplied to the data driver 13, and the data driver 13 can latch only one line worth of image data signals at a time, duration necessary for transmitting one line worth of data signals of image data from the controller 11 to the data driver 13 needs to be equal to or less than T.
Subsequently, after elapse of the duration T from the emission start of the first line, the shift register 61-1 shifts the ON signal corresponding to the scan start pulse to the shift register 61-2. The scan start pulse is an ON signal having the width equivalent to one cycle of the scan clock, so the shift register 61-1 shifts the ON signal (High) corresponding to the scan start pulse to the shift register 61-2, following which receives supply of an OFF signal (Low). Accordingly, at this time, the switching transistor 62-1 is turned OFF. In response to the ON signal corresponding to the scan start pulse, the shift register 61-2 turns on the switching transistor 62-2, thereby applying voltage to the scan electrode of each of the emission elements 21 on the second line. Subsequently, based on the output from the data driver 13 at that time, each of the emission elements 21 is lit for predetermined duration.
Subsequently, after elapse of the duration T from the emission start of each line, the emission of the line thereof is completed in order to start emission for the next line, and the ON signal corresponding to the scan start pulse is shifted to the shift registers 61-3 through 61-c. 
Data transmission to the data driver 13, and the emission timing of each line will be described with reference to FIG. 5. The image data signal on the k'th line (k is a positive integer which is equal to or greater than 1 and also equal to or smaller than the number of lines c making up one frame) is supplied from the controller 11 to the data driver 13. As described above, in a case wherein the emission duration of each line is T, duration necessary for data transmission of one line needs to be equal to or smaller than T. Subsequently, data transmission and latching of the image data signal on the k'th line ends, and at point-in-time t(k+1) after elapse of the duration T from the transmission start point-in-time tk of the image data signal on the k'th line, the k'th line is lit, and supply of the image data signal on the k+1'th line is started. Subsequently, data transmission and latching of the image data signal on the k+1'th line ends, and at point-in-time t(k+2) after elapse of the duration T from the transmission start point-in-time t(k+1) of the image data signal on the k+1'th line, the k+1'th line is lit, and supply of the image data signal on the k+2'th line is started. Subsequently, data transmission and latching of the image data signal on the k+2'th line ends, and at point-in-time t(k+3) after elapse of the duration T from the transmission start point-in-time t(k+2) of the image data signal on the k+2'th line, the k+2'th line is lit, and supply of the image data signal on the k+3'th line is started. Hereafter, similarly, while a certain line is lit up to the last line of the frame thereof, the image data signal on the next line is supplied.
In FIG. 5, with that the emission cycle of each line as fH, the transmission cycle of data and the horizontal frequency of the display of the display portion 12 also become fH, and with the number of pixels of one horizontal line as a, and the number of gradations at the emission of each pixel as D, an emission clock frequency fp is represented with fp=fH×D, and a data transmission clock frequency fd is represented with fd=fH×a.
Specific description of the overall operation of the display device 1 described above will be as follows.
First, the image data on the first line is transmitted to the shift register 41 of the data driver 13 from the controller 11, and is latched at the latch 42. Subsequently, in response to supply of the scan start pulse, the scan driver 14 turns on the first column of the display portion 12, i.e., the switching transistor 62-1 connected to the scan electrodes of the column of the emission element 21-1-1, emission element 21-1-2, and so on by the period ofdisplay duration of one frame/number of scan lines=duration T. 
Subsequently, at that time, the first column of the display portion 12, i.e., the emission element 21-1-1, emission element 21-1-2, and so on are lit with the brightness corresponding to the ON duty of the driver 44 controlled by each comparator 43 of the data driver 13. While emission of the first column of the display portion 12 is performed, the image data on the second line is transmitted to the shift register 41 of the data driver 13, and is latched at the latch 42.
Subsequently, at the next timing thereof the scan driver 14 turns on the second column of the display portion 12, i.e., the switching transistor 62-2 connected to the scan electrodes of the column of the emission element 21-2-1, emission element 21-2-2, and so on during the period of the duration T. Subsequently, at that time, the second column of the display portion 12, i.e., the emission element 21-2-1, emission element 21-2-2, and so on are lit with the brightness corresponding to the ON duty of the driver 44 controlled by each comparator 43 of the data driver 13. While emission of the second column of the display portion 12 is performed, the image data on the third line is transmitted to the shift register 41 of the data driver 13, and is latched at the latch 42.
Hereafter, similarly, the switching transistor 62 connected to the scan electrodes on the k'th column is turned on during the period of the duration T, and at that time, the k'th column of the display portion 12 is lit with the brightness corresponding to the ON duty of the driver 44 controlled by each comparator 43 of the data driver 13. Subsequently, while emission of the k'th column of the display portion 12 is performed, the image data on the k+1'th line is transmitted to the shift register 41 of the data driver 13, and is latched at the latch 42. Subsequently, such processing is repeated one line at a time, thereby displaying the image data of one frame.
With the simple matrix method described with reference to FIGS. 1 through 5, the configuration is simple, so the panel can be manufactured inexpensively, but as described above, the emission duration of one pixel at one frame of an image is
display duration of one frame/number of scan lines, and accordingly, sufficient brightness may not be able to be obtained. Accordingly, with the flat display field, not the simple matrix method but the active matrix method, such as TFT (Thin Film Transistor), has been frequently employed.
With the active matrix method, signal input is performed as to only the line being scanned, but a TFT is provided for each emission element of each of RGB included in one pixel, whereby applied voltage can be maintained even during a non-scan period. That is to say, the active matrix method is a hold-type driving display method whereby each of the sub pixels can maintain constant brightness up to the next scanning.
Heretofore, of display devices performing matrix driving, in order to perform halftone display, some display devices are configured to apply a scanning signal to multiple line electrodes simultaneously in a duplicated manner (see Japanese Unexamined Patent Application Publication No. 2-25893).
Also, some display devices are configured to obtain sufficient brightness even using the simple matrix method by dividing a displays portion into two in the horizontal direction, providing driving drivers of the data electrodes of two regions separately, and light-emitting each of the two regions one line at a time at the same timing, i.e., by light-emitting two lines on one screen simultaneously (see Japanese Patent Application No. 2003-280586).